U.S. Geological Survey (USGS) scientists have developed a new method for measuring the ability of an aquifer to store and transport water and contaminants without interrupting ongoing pump-and-treat remediation systems. Aquifer tests are traditionally used to measure subsurface rock properties that control the flow of groundwater and the movement of contaminants. The results are used, among other things, to design and optimize remediation systems. However, conducting a standard aquifer test entails pumping a well and observing the effects at other non-pumping wells nearby, which can be problematic at contamination sites with ongoing pump-and-treat remediation systems. Shutting down the system, even for a short time, could potentially compromise the hydraulic containment of contaminated groundwater. Conducting such a test in a contaminated area also requires disposing of contaminated water generated by the test. Therefore, in many cases standard aquifer tests are not conducted after remediation systems are installed because of these problems. The new method takes advantage of the pump-and-treat system, and entails short-term shutdown of just one pumping well in a multi-well system and observation of water-level recovery in other nearby monitoring wells. Conducting aquifer tests in this manner has several advantages, including:

no additional contaminated water is removed from the aquifer;

hydraulic containment of contaminants remains intact; and

multiple wells can be used to collect data, which produces more robust results.

This well-shutdown method was tested at the former Naval Air Warfare Center, West Trenton, New Jersey, where a pump-and-treat remediation system limits off-site migration of trichloroethylene that is present in the fractured bedrock underlying the site. Analysis of the aquifer tests showed that the new method yields valuable information about the movement of water and contaminants at the site. The new method is being used to evaluate the performance of the pump-and-treat system. Environmental professionals can use this new approach to collect aquifer property data at sites across the Nation with pump-and-treat remediation systems.